prEN IEC 62271-205:2026

1.1 General
This part of IEC 62271 series applies to service conditions, rated characteristics, general structural requirements and test methods of compact switchgear assemblies, mobile substations and prefabricated substations, for indoor and/or outdoor installations in systems having rated voltages above 52 kV and service frequencies up to and including 60 Hz.
1.2 Compact switchgear assemblies
In general, compact switchgear assemblies consist of at least one mechanical switching device directly connected to or sharing components with one or more other devices such that there is an interaction between the functions of the individual devices.
The devices, defined by IEC standards, which can be a part of a compact switchgear assembly are exemplary listed below and is not be limited to:
NOTE To simplify the reading of this document, the term "switching device" is used instead of the term "mechanical switching device".
Switching devices:
– Circuit-breakers
– Disconnectors/Earthing switches
– Switch-disconnectors
– Disconnecting circuit-breakers
Devices:
– Instrument transformers
– Surge arresters
– Bushings
– Insulators
– Cable connections
– Transformer connections
The interaction between devices might be due to proximity, sharing of components or a combination of both. The assemblies can contain devices of air insulated switchgear (AIS) only or a combination of part of AIS and part of gas-insulated metal-enclosed switchgear (GIS), so called mixed technology switchgear (MTS) and can be delivered entirely prefabricated or partially assembled.
Each switching device forming a part of a compact switchgear assembly shall comply with the relevant individual standard. If a part of the compact switchgear assembly is formed by gas-insulated metal-enclosed switchgear devices, the requirements of IEC 62271-203:2022 apply.
The parts of this document relevant for compact switchgear assemblies do not apply to switchgear assemblies (for fixed or mobile purpose) consisting solely of GIS which are covered by IEC 62271-203.
It is not possible to define all potential arrangements of compact switchgear assemblies. Four examples are shown for information in Annex A.
1.3 Prefabricated substation and mobile substation In general, a prefabricated substation is a high-voltage assembly, comprising of different functional type-tested modules, assembled off-site in a factory and then transported to its final location for installation. The majority of the assembly and testing operations which are normally carried out at site are completed before delivery in order to shorten site works. A prefabricated substation is based on functional modules and consists at least of a power transformer module and/or a high-voltage switchgear and controlgear module. Further functional modules, which may be part of a prefabricated substation, are listed below but shall not be seen as conclusive:
– Protection and control module
– Medium-voltage module
– Lightning protection
– Power cable
Compact switchgear assemblies can be an integral part of the high-voltage switchgear and controlgear module and can be therefore part of a prefabricated substation.
A mobile substation is a prefabricated substation designed and intended to be transported during lifetime by use of an adequate vehicle. Requirements for the vehicle can be linked to local regulations and are not in the scope of this document.
In general, it is not feasible to specify every possible configuration of prefabricated and mobile substations. Annex B provides more information on mobile substations and Annex C on prefabricated substations.
NOTE For the use of this document high voltage (IEC 60050-601:1985 [2], 601-01-27) is the rated voltage above 1 000 V. However, medium voltage (IEC 60050-601:1985 [2], 601-01-28) is commonly used for distribution systems with voltages above 1 000 V and generally applied up to and including 52 kV. For a better understanding in reading this document the term “medium voltage” will be used where necessary.